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On a ZZ4, a "TPI from a 305" would have the fuel rails and hoses left from it. Okay, maybe the plenum if ported. EGR valve perhaps. Thermostat housing. Distributor.

The ZZ4 cam is way too much for a TPI already, if you see what I mean. Sure, it'll run, but it will run out of breath at 5000 rpm - the ZZ4 wants more. TPI's don't care much for cam lope, either.

You're looking at things like a Bigmouth base, shorter runners, bigger TB, bigger injectors, and a PROM that is matched to the final combo, at a minimum. Can we assume you've already figured out what you need to do with the exhaust?

I think you need to completely rethink this project. At least, do a lot more homework first. It's okay to do some of that by asking questions here - don't get me wrong. Just don't be surprised when you get frank answers (I'm really not trying to put you down, just want to get you thinking).

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82 Berlinetta, orig V-6 car, now w/86 LG4/TH700R4, 2300 stall TC. Ported World 305 heads, Crane PowerMax 2050 cam. ZZ3/4 intake, oil pump, pan & baffle. Accel HEI SuperCoil & module. Hooker 2055 headers, 3" Catco cat & 3" catback w/dual-opposite Flowmaster 80. 2.93 limited slip. Spohn SFCs waiting to be installed. AMSOIL syn lubes bumper-to-bumper. Daily year-round driver. Best ET, speed TBD...
57 Bel Air, my 1st car. '66 396, 9.7:1 forged TRWs, Weiand Action+, Holley 750VS w/4150 conversion, GK 270 cam, Magnum rockers, Jacobs Omnipack, 1-3/4" Hedders & 3" Warlocks, TH400 w/TCI Sat Night Special conv & Trans-Scat shift kit, MegaShifter, 3.08 8.2" 10-bolt w/Powertrax, AMSOIL syn lubes bumper-to-bumper. Idles smooth @ 700 RPM in D. Best 15.02/95.06 @ 5800' Bandimere (corrected 13.93/102.4 @ sea level).

I have a ZZ-4 now with the regular cam and all high flow TPI pieces. I've heard of people running the ZZ-4 with a stock TPI too and not having too many problems but that's with the regular cam. On a tight budget you could get away with using almost all the stock TPI stuff. If you change the cam then I'd look into high flow parts. The few things I'd definitely change though are the knock sensor and knock module to 350 units. I'd also get an AFR. I'm currently using the stock 305 19lb injectors. I also have no emissions equipment.

The prom is another story. I have a $500 custom prom and I'm not happy with it. The aftermarket proms suck unless the tuner has your car there to work with and burns a custom one like that. If you're not burning your own the aftermarket is your only alternative. Search the boards and see who people recommend the most. A good exhaust is a must, headers and 3" piping will work fine. No cat needed since it's non-emissions (that's how I looked at it)


For the 375HP area you can get the LT-4 Hot cam kit which includes the 1.6 rockers. Remember though that the rating of 385HP-394HP with that cam is with a carb setup running in the perfect conditions. The stock cam doesn't sound hald bad though. You won't fool anyone telling them it's your stock 305.

Alot of people say the TPI won't pull past 5,000 and that's not true. It does have limits but with my high-flow parts the engine pulls till about 5,300-5,500. The ZZ-4 is rated to 5,800rpm but that's past peak HP. I don't think you'll get the max. 355HP with the TPI without serious custom chip work. However, TPI loves torque and this motor makes peak at around 3,500. With the TPI my car hauls just fine. This could turn into a debate but look around, you'll see it's not so bad. I will say a carb would have been so much easier but in my opinion a TPI is alot nicer. As far as it not working I went a best 13.80 with the 2.73 gears, crappy radial tires, stock suspension, freezing weather, and a late 2-3 shifting tranny.

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1986 T-Top Z-28, ZZ-4 Crate Engine, Complete High Flow TPIS TPI, SLP 1-3/4" Headers, 3" Exhaust, Richmond 3.73's, Moser Axles, Auburn Pro-Series Diff, 2800rpm 10" Non-Lockup Conv., 90/10 Front's, 40/60 Rears, Spohn LCA's, LCA's brackets, SSM SFC.


[This message has been edited by ryn28 (edited December 03, 2001).]

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The ZZ4 was intended to be a carb engine, although plenty of people have gone TPI with it (including a racing buddy of mine). You just aren't going to do it with factory TPI parts, that's all.

And ryn28, nobody says TPI can't go above 5000 RPMs. Again, it's the factory TPI that can't go above 5000 RPM. This same racer buddy of mine shifts at 6 grand - the only factory TPI parts he has left are fuel rails, fuel lines, and EGR valve (and ECM if you don't count the chip, & plenum if you don't count porting).

I hear what you're saying about the TPI dropping off around 5,000rpm, that's way I stated mine WITH the high flow parts pulls further then that. As far as the ZZ-4 being "intended for a carb" that's only partially true. If the system is setup right, using a cam that works within the TPI's parameters, etc. you could put it on almost any engine. It's like anything else, if it's built with the wrong parts or tuned wrong nothing will work well, carb or FI.

28, I'm an engineer, so when I say "intended for...", I mean that's what they had in mind when they designed it. If you'll notice, all of their literature talks about "75-older or off-road use only", and they only offer turn-key ZZ4s with a carb.

That doesn't mean you can't make it work in other ways. Both what you did and what I was saying proves that "intended" and what actually happens are two different things.

Tom was talking about just putting a 305 TPI on the crate engine and living happily ever after. I was simply trying to bring some reality back into the discussion. Your actions showed you had done your homework first.

Cool. I wish more people on the boards could learn how to have a discussion like we had without it becoming a stupid arguement. This is how we learn.

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